Sheeting for wrapping various goods and articles on the market has conventionally had patterns and pictures formed by such methods as printing and hot-stamping. The exterior of containers such as cartons or displays for goods have also been provided with various patterns by printing, hot-stamping and other suitable methods in order to improve the image of the goods of interest. However, the patterns and pictures provided on the conventional wrapping sheets, containers and displays are two-dimentional and are incapable of completely satisfying the recent growing need of the industry for improving the aesthetic appeal of packaging materials such as wrapping sheets and cartons, as well as displays on goods. To meet this need, it is desired that patterns, pictures and other images be adapted to vary in shape by themselves.
Under these circumstances, hologram forming sheets that have preformed hologram patterns are used as wrapping sheets. A conventional process for producing such hologram forming sheets consists of embossing a resin sheet with a stamper that has a hologram relief formed thereon, and then forming a metal layer on the patterned surface of the resin by vacuum evaporation. In this process, however, the formation of a hologram pattern on the resin sheet by embossing involves reheating of the once formed thermoplastic resin sheet. Such an extra step not only reduces the operational efficiency but also causes a substantial energy loss, thus making said process unsuitable for large-scale production of hologram forming sheets. With a view to solving this problem, an improved process for producing a hologram forming sheet has been proposed, in which process a hologram with a surface relief can be obtained by extrusion molding technology (see Unexamined Published Japanese Patent Application No. 191872/1987). However, if the resin sheet on which a hologram pattern is to be formed has low hardness, the hologram forming sheet produced by this process has low machinability (i.e., adaptability for mechanical working) since the hologram pattern will be damaged or lost during the formation of a hologram or in subsequent process.